I think ring slings are the easiest - even for newborns! - but only if you can get someone to show you in person and in detail how to do it. I never got the hang with watching youtube videos and looking at diagrams. I did manage to at least get the weighted doll in the right position when shown in person.

I have a beco soleil and cracked feeding in the sling at about one month. It was a total game changer at 15 months DS still happily feeds in the sling. A word of warning though, we are so good at doing it discretely now that the occasional stranger has been know to peek in the sling for a look at the baby and be confronted with my nipple as DS spots it out to say hi to them...